[SIPForum-discussion] Early media...Use.

[Ashwin Kumar]

Does any one has a trace for early media? 

Thanks
Ashwin


----- Original Message ----
From: vinoth <Vinoth.E at mobax.com>
To: Naresh Parmar <parmar.naresh at gmail.com>; discussion at sipforum.org
Sent: Saturday, February 3, 2007 9:20:49 AM
Subject: Re: [SIPForum-discussion] Early media...Use.


Hi Naresh,
           A Media Session is established only after receiving 200 OK response(& ACK). Now how will you hear a ring tone or busy tone?.

           So for this we use 183 to indicate only the progress of the Session.

           Unlike a 180, 181, or 182 response, 183 does not convey any specific information about the status of the INVITE. 

           The 183 Session Progress response indicates that information about the progress of the session (call state).

           It may be present in a message body or media stream. 

           A 183 is an end-to-end response and does establish a dialog (must contain a To tag and Contact). 

           A typical use of this response is to allow a UAC to hear ring tone, busy tone, or a recorded announcement in calls through a gateway into the PSTN. 

           This is because call progress information is carried in the media stream in the PSTN.


  Regards,
Vinoth Kumar.
Mobax Networks, Coimbatore.

   

---------- Original Message ----------------------------------
From: "Naresh Parmar" <parmar.naresh at gmail.com>
Date:  Fri, 2 Feb 2007 13:05:26 -0500

>Yes, early media in fact is exchange of sdp parameters through 183 session
>progress message before getting the final 200 OK message. One typical use of
>it would be to play a music for the calling party by the proxy server
>whenever it sees a call by a given party. So that means when the call is in
>progress (i.e. ringing at the called party), the calling party hears the
>music as decided by the proxy server as there is an early media session
>established between the proxy and the calling party. When the called party
>eventually answers the call, the early media session is closed and the final
>sdp exchange happens between the calling party and the called party (as in
>the 200 OK message), based on which media streams are opened.
>
> Another use of early media would be to have a complete session description
>exchanged through 183 session progress message between the calling and the
>called party, and open the media stream immediately after getting the 200 OK
>response (200 OK does not carry sdp normally in this case as its already
>been conveyed through the 183 session progress), this avoids processing the
>sdp after receiving 200 OK and thus establishes the call more quickly.
>
>No, early media is not necessary unless you have some specific requirements
>to do so.
>Hope this helps.
>
>
>On 2/2/07, nithya kumar <nithyakr at huawei.com> wrote:
>>
>>
>>
>>
>>
>> Hi Sip Experts,
>>
>>               Can some one explain the exact use of Early media ?????
>> 
Early media is nothing but exchange of SDP parameter Before call
>> Begins(means Dialog begins)
if so Re-invite to both Caller and callee before
>> call starts (dialog starts) also doing SDP exchange functionality
.!!!! 

>>
>> --- if so exact use of early media????
>>
>> -- early media is compulsory ??
>>
>>
>>
>>
>>
>> Nithya Kumar.R
>>
>> Huawei Technologies India Pvt Ltd,
>>
>> Bangalore
>>
>> Mob-9986035813
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>
>
>


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